Path Following for Autonomous Tractor under Various Soil Conditions and Unstable Lateral Dynamic

Lighten the job of the agricultural vehicle operators by providing some autonomous functions is an important field of research, whose most important challenges are to keep the accuracy and optimize the yields. Autonomous navigation of a tractor involves the control of different kinematic and dynamic subsystems, such as the tractor positions, the yaw angle and the longitudinal speed dynamics. The dynamic behavior is highly correlated with the soil conditions of the agricultural field. This paper proposes a Lyapunov's stability theorem (LST) based kinematic controller for path following in autonomous tractor. Moreover, a Fuzzy-PID controller is employed to control the longitudinal dynamic, and a linear quadratic regulator (LQR) based state-feedback controller to handle the lateral dynamic behavior. Numerical simulation results in MATLAB software show the proposed algorithms can handle the uncertainty of the soil conditions represented by the variations of the rolling friction coefficient.